当我在 Apache Karaf 3.0.4 中获得 BasicDataSource 时出现 ClassCastException

Question

我在 Apache Karaf 3.0.4 中工作，我的问题是当我尝试从数据源（我有一个数据源列表）获取属性时出现错误，我正在使用此代码

    BundleContext bundleContext = FrameworkUtil.getBundle(MyController.class).getBundleContext(); 
    ServiceReference[] serviceReferences =bundleContext.getAllServiceReferences("javax.sql.DataSource", null); 

     //and in this part 

     for (ServiceReference serviceReference : serviceReferences) { 
            Object jndi = serviceReference.getProperty("osgi.jndi.service.name"); 
            if (jndi != null) { 
                serviceReferenceDataSources.add(serviceReference); 
                Object service = bundleContext.getService(serviceReference); 
                //here the code fails 
                BasicDataSource basicDataSource = (BasicDataSource) service; 

             } 
      } 

这是堆栈跟踪

java.lang.ClassCastException: Proxyfcb4dd22_6103_4978_b41b_0bacfb118a66 cannot be cast to org.apache.commons.dbcp2.BasicDataSource 

我需要 BasicDataSource 对象来获取它们的属性（maxTotal、用户名、url、validationQuery、initialSize、maxWaitMillis）

最后，当我尝试强制转换为“javax.sql.DataSource”时，此代码有效，但我需要此对象 BasicDataSource。

编辑 1

这是我的蓝图

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0"
     xsi:schemaLocation="
        http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0 http://aries.apache.org/schemas/blueprint-cm/blueprint-cm-1.0.0.xsd
        http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">

  <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
      <property name="driverClassName" value="${jdbc.driverClassName}" />
      <property name="url" value="${jdbc.url}" />
      <property name="username" value="${jdbc.username}" />
      <property name="password" value="${jdbc.password}" />
      <property name="initialSize" value="${jdbc.initialSize}" />
      <property name="maxTotal" value="${jdbc.maxTotal}" />
      <property name="maxWaitMillis" value="${jdbc.maxWaitMillis}" />
      <property name="validationQuery" value="${jdbc.validationQuery}"/>
      <property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>
      <property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>
  </bean>

  <service interface="javax.sql.DataSource" ref="dataSource">
    <service-properties>
        <entry key="osgi.jndi.service.name" value="jdbc/ejemplodb"/>
     <entry key="datasource" value="ejemplodb"/>
    </service-properties>
  </service>

如果我在控制台中打印此代码

  ...
    Object service = bundleContext.getService(serviceReference);
    logger.debug("Service getClass() ", service.getClass());
    System.out.println("Service in println" + service);
  ...

我明白了

  Service getClass() Proxy79d23ceb_cee2_4031_bdc3_13fd572cdf8c
  Service in println org.apache.commons.dbcp2.BasicDataSource@7f753504

希望你能帮助我，谢谢。

Answer 1

根据您的请求，返回的服务将是 javax.sql.DataSource 类型。在那里转换到 apache 的基本数据源是无效的。但只要您只需要数据库连接，您应该可以使用 javax.sql.Datasource？

javax.sql.DataSource basicDataSource = (javax.sql.DataSource) service; 

如果您需要服务的类型为 BasicDataSource，您可能最终会更改 bundleContext.getAllServiceReferences("javax.sql.DataSource", null); 以查找 BasicDatSource，并将 BasicDataSource 的声明更改为类型 BasicDataSource 而不是类型javax.sql.DataSource.